Flooding Hamas tunnels could harm Gaza’s freshwater for generations, warns academic

Experts call on defense establishment to carefully weigh environmental impacts of reported plan to flush terrorists out of vast underground network

Sue Surkes is The Times of Israel's environment reporter

Soldiers guard the entrance to a Hamas tunnel in the Gaza Strip, in a handout photo published November 9, 2023. (Israel Defense Forces)
Soldiers guard the entrance to a Hamas tunnel in the Gaza Strip, in a handout photo published November 9, 2023. (Israel Defense Forces)

Environmental experts called on the defense establishment Tuesday to carefully weigh the long-term environmental implications of reported plans to flood the immense network of tunnels in the Gaza Strip with seawater to flush the terrorists out.

Quoting US officials, The Wall Street Journal reported Monday that the Israeli army last month set up five large water pumps near the al-Shati refugee camp in Gaza City, which are capable of flooding the tunnels within weeks by pumping thousands of cubic meters of water per hour into them.

Under normal circumstances, rain falls to earth and percolates down into subterranean storage areas, or aquifers. This groundwater is pumped up into wells to supply drinking water.

Gaza is home to more than two million people and is one of the most densely populated places on earth. The enclave’s only sweet-water supply comes from a shallow aquifer running parallel to the Mediterranean coast.

That has been so overpumped and the subterranean water levels have dropped so far that seawater has entered the aquifer and mixed with the little sweet-water that remains.

The aquifer’s water quality has been further eroded by sewage, and agricultural chemical runoff, to the extent that 97 percent of Gaza’s freshwater no longer meets World Health Organization (WHO) water quality standards.

Emeritus Prof. Eilon Adar of Ben-Gurion University. (Dani Machlis/BGU)

Even before the war, most Gazans relied on private water tankers and the yield of small desalination plants for drinking water.

Following  Hamas’s invasion of Israel on October 7, in which terrorists murdered some 1,200 people and kidnapped 240 others, Israel turned off three pipelines carrying drinking water into the strip. Under US pressure, it subsequently reopened two of them, and during the recent pause in fighting to release hostages, allowed in more of the fuel needed to pump the water from the Israel-Gaza border into the enclave.

Still, Gazans are desperately short of clean water.

Prof. (Emer.) Eilon Adar of the Zuckerberg Institute for Water Research at Ben-Gurion University of the Negev, in southern Israel, said that further potential ecological damage to Gaza’s aquifer by flooding the tunnels would depend on the quantity of water and the reach.

Stressing that he was neither an expert on the issue nor involved with the Defense Ministry’s reported plans, he said that the pumping of a relatively small amount of seawater affecting the area between the Mediterranean coastline and the point where sea- and sweet-water were mixing anyway would have minimal consequences.

That latter point lies anywhere from tens to several hundreds of meters inland from the Gazan shore.

But if several million cubic meters were pumped into the tunnels, and seeped into the aquifer, “the negative impact on groundwater quality would last for several generations, depending on the amount that infiltrates into the subsurface,” he said.

Israel would hardly feel the effect, he went on, because the coastal aquifer’s water flows from Israel to Gaza.

Nevertheless, Adar added, he would “hesitate about destroying a massive natural resource.”

“As a citizen, despite the disaster that we experienced on October 7, I still think that in the long run — and we have to think of the future — it would be politically and morally incorrect to have a thirsty neighbor,” he said.

Palestinians line up to refill water in Rafah refugee camp in the southern Gaza Strip, on October 14, 2023. (Mohammed Abed/AFP)

Another water expert, who asked not to be named, said tunnels, carved out of porous sand, would need to be flooded several times.

Some of them were built to bring terrorists into Israel, he added. If seawater entered those sections, it could salinate Israeli wells close to the Gaza border.

Prof. Hadas Mamane, who heads the Environmental Engineering Program at Tel Aviv University, said the environmental impacts of all options for destroying the tunnels had to be considered, and their effects on the air, water, soil, hydrology and ecology tested in advance.

Blowing up weaponry in the tunnels could also have environmental consequences, she added, if dangerous toxic materials and heavy metals seeped into the groundwater.

“You don’t look at what’s best but what’s the least worst solution,” she said.

Both the IDF and the Defense Ministry said they had no comment.

The officials cited by The Wall Street Journal said Israel had alerted the US about the plan last month, but had not yet decided on whether to implement it.

The report said opinions in the Biden administration about the idea were mixed.

It also noted it was unclear whether the IDF would move to flood the tunnels before all of the hostages that Hamas and other Palestinian terror groups abducted during the October 7 onslaught were freed, due to the apparent risk that would be posed to hostages being held underground.

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